Lost Treasures

Opening

Lost Treasures is a small, calm arcade toy built for js13k 2017 (theme: "lost") — steer a little boat across a stylised, foggy sea, dive down, and recover a handful of lost coins scattered across the seabed. It's exactly the size and scope you'd expect from a 13-kilobyte competition budget, and it makes surprisingly good use of that budget visually: real-time shadow mapping, a rolling procedural sea surface, and pyramids fading into fog on the horizon.

Controls, confirmed the hard way

This one needed real investigation rather than a glance. On first touch, the two circular on-screen controls didn't visibly do anything obvious, and the "Find N lost coins!" banner text never changed no matter what was pressed — which turned out to be a red herring, since that text only updates when you actually recover a coin, not on movement. Reading the actual boat physics (player.v, player.depth, player.matrix) directly out of the running game confirmed the real story: the movement joystick lives on the right side of the screen and the dive button on the left — the reverse of the layout used by most twin-control mobile games — and once pressed in the correct spot, both work immediately and correctly. A right-side joystick drag measurably increased the boat's forward velocity and moved its world position; a left-side press measurably increased dive depth. Desktop arrow keys produce the identical physics response with zero console noise.

One real, if minor, issue turned up during that investigation: every touch interaction throws Unable to preventDefault inside passive event listener due to target being treated as passive in the console. The game's touch handler calls event.preventDefault() from a listener the browser has decided to treat as passive, so the call silently does nothing. It didn't block movement in testing here, but it's exactly the kind of quiet inconsistency that can behave differently across browser versions, and it's worth a developer's attention even though it isn't disqualifying today.

Presentation

For a competition entry this size, the visuals genuinely impress: dynamic shadows cast by the boat and scenery, a semi-transparent rolling sea surface, distant pyramids dissolving into fog — a lot of atmosphere for very little code. It's let down a little by very sparse sound and a short, single-idea play loop with nothing to keep you coming back once you've found the coins a couple of times.

Final Verdict

A tiny, good-looking piece of js13k history that holds up on both desktop and phone once its unconventional control layout is worked out — controls that were confirmed here to genuinely function, not just assumed to. It won't hold anyone's attention for long, but it's a pleasant few minutes and a fair example of what the competition's constraints can produce. Worth a look.